Certified Rhythm Analysis Technician (CRAT) Practice Exam

The occurrence of a premature ventricular contraction (PVC) during the relative refractory period is referred to as the R-on-T phenomenon. This phenomenon is critical in understanding the timing of cardiac events and can lead to significant clinical implications.

During the relative refractory period, the cardiac muscle is still somewhat excitable, meaning that it can respond to electrical stimuli, but with a higher threshold. If a PVC occurs during this time, it can lead to an arrhythmia, as the timing of the premature beat can disrupt the normal rhythm of the heart, potentially resulting in more serious conditions such as ventricular tachycardia or fibrillation.

Recognizing the R-on-T phenomenon is essential for healthcare professionals, as it highlights the importance of monitoring the timing of PVCs relative to the cardiac cycle, especially in patients with underlying heart conditions. Understanding this specific timing can help in diagnosing and managing rhythm disorders effectively.